Flexible container of plastic material



June 1968 KARL-HEINZ SIEGEL 3,389,733

FLEXIBLE CONTAINER OF PLASTIC MATERIAL Filed June 6, 1966 FIG. 7

FIG. 2

2 Sheets-Sheet 1 June 25, 1968 KARL-HEINZ SIEGEL 3,389,733

FLEXIBLE CONTAINER OF PLASTIC MATERIAL 2 Sheets-Sheet 2 iled June 6, 196

United States Patent "ice 3,389,733 FLEXIBLE CONTAINER 0F PLASTICMATERIAL Kari-Heinz Siege], Schwaig via Narnberg, Germany, as-

signor to ASF Gleitverschulss G.rn.b.H., Nnrnberg, Germany Filed June 6,1966, Ser. No. 555,378 Ciaims priority, application Germany, July 7,1965, S 98,059 3 Claims. (Cl. 150-3) ABSTRACT OF THE DISCLOSURE Aclosure for a bag of plastic material of the type comprisingcomplementary profiled strips longitudinally provided within the bagopening and which can be closed with one another by pressure and whichcan be opened at the opening of the bag by pulling apart the wallsthereof. The improved closure comprises one strip having a cross sectionincluding only one book facing the interior of the bag. Thecomplementary strip is secured to the other wall of the bag and includesa double strip comprising a first strip portion having a flat surfaceresting against the back of the hook when the strips are closed togetherand a second strip portion provided with a hook profile which iscomplementary to and engages when closed the hook of the first-mentionedstrip.

This invention relates to a flexible wrapper of plastics material, whichconsists preferably of a tube section which has been obtained by formingtransverse heat-sealed seams in a tubing of thermoplastic material,which tubing has on the inside two longitudinally extending, profiledstrips, which can be hooked into each other under pressure. Suchwrappers of plastics material should be capable of being opened whenrequired and to be closed in a simple manner when the contents or partthereof has been removed. Thus, it is an object to provide durable andreusable wrappers.

A known bag has walls consisting of plastics material sheeting and isprovided near its edge between the mutually opposite inside surfaces ofits walls with fastener elements, which can be caused to interengage andembrace each other. The dimensions and/or shapes of said elements areselected so that the resistance to their separation by an internalpressure of the bag is a multiple of the force which is required fortheir interengagcment or for their separation by an action which isexerted from the outside on the edge-s of the walls. This definition ofthe bag described in a prior publication contains only a detailedstatement of the problem but does not disclose a solution to a personskilled in the art. When the subject matter of the prior publication isascertained from the contents of the description, it is apparent that asolution of the problem set forth resides in that the head of a ribconstitutes an unsymmetrical, enlarged portion, which on both sides ofthe root forms surfaces for a hooklike engagement with the associatededges of a groove, and that one of these surfaces, which is on theinside of the rib, has a higher inclination relative to the wall of thebag than the surface on the outside of the rib.

The present invention is based on the experience, which 3,389,733Patented June 25, 1968 has been obtained in practice and by tests, thatthe known hooking elements of the flexible wrapper of plastics materialdescribed initially hereinbefore are suflicient to afford the desiredresistance to a force which is produced by an internal pressure.

In view of this prior art, it is an object of the inven tion to providea wrapper which consists of plastics material and which has hookingelements having enlarged interengaging surfaces and in which aresistance of hooking elements need not be overcome to open the package.

In a flexible wrapper of plastics material of the kind set forthinitially hereinbefore, this object is accomplished by the invention inthat one profiled strip consists of a unilateral hook, which is directedtowards the inner part of the bag, and the other profiled stripcomprises two flanges, which extend at right angles from the insidesurface of the wrapper and are disposed on opposite sides of the hook ofthe opposite profiled strip, that flange which is disposed on theoutside of the fastener being arranged to engage the back of the "hook,and that flange which is disposed on the inside of the fastenercomprising a unilateral hook tip, which has a concave or re-entrantinside surface. The partial object of the invention to provide a wrapperwhich consists of plastics material and has hooking elements havingenlarged interengaging surfaces is accomplished in that that flange ofthe one profiled strip which is disposed on the inside of the fastenerconsists of a unilateral tip having a concave inside surface hook. Thisresults in a larger space between the two flanges which are to beinterengaged. For this reason, the tips of the hooks may have a lengthwhich is sufficient to ensure a reliable closure. The further partialobject of the invention to enable an opening of the wrapper without needfor overcoming a resistance which is generated because two flexiblehooking elements must be disengaged by bending, when they rub on eachother, is accomplished in that the flange disposed on the outside of thefastener does not form a hook and the intermediate flange disposed onthe opposite inside surface of the wrapper has no hook tip on theoutside of the fastener. This profiled configuration takes account ofthe fact that any user of a wrapper of flexible plastics material inopening the same unconsciously performs with its hands a rotationalmovement about the longitudinal axes of the two profiled strips whichhave been hooked together so that the two unilateral hook elements aredisengaged without need for a continually repeated expansion of thefemale part. A forcible separation of the two interengaged hook elementsis unconsciously avoided. For this reason, the fastener according to theinvention is less subjected to wear and for this reason has a longerlife. Another advantage of the wrapper according to the inventionresides in that a reliable fastener is obtained, which has only two hookelements whereas four hook elements were required in the prior art.Thus, it has been recognized that a hooklike enlargement at the flangeend is required only on the inside of the fastener. Compared to the useof hooks in the form of arrowheads, this results in a saving of materialand in a reduced space requirement for the enlarged portions. Inflexible wrappers these aspects are of great practical importancebecause the endless tubing is divided on automatic bag-making machinesby a fusion cutting and sealing operation into individual wrappers.

This results in difficulties when excessively thick profiled strips areused. These advantages become also apparent when the tubing of plasticsmaterial provided with profiled strips is supplied to a customer beforeit has been processed into individual wrappers. For such supply, thetubing is wound up in rolls. These rolls will now require a smallerspace and have a lower weight.

In a particularly preferred embodiment of the invention, each of theinterengaging surfaces of the two hooklike flanges includes an acuteangle with the associated inside surface of the wrapper. This willensure a particularly good closure in spite of the action of forceswhich might arise in the interior of the wrapper and tend to open thefastener. In view of the design of the profiled strips according to theinvention, the fastener elements will not unduly resist an opening ofthe fastener from the outside.

In a further embodiment of the invention, the female profiled strip hasa smooth back. This affords the advantage that the two profiled stripscan be more easily interengaged than in known wrappers where the femaleprofiled strip is tiltable relative to the inside wall of the wrapper.

An embodiment of the invention will now be described by way of examplewith reference to the accompanying drawing, in which FIG. 1 is asectional view showing a cut-off portion of a wrapper according to theinvention with the two profiled strips interengaged.

FIG. 2 is a diagrammatic view showing the die which is employed in themanufacture of the wrapper according to the invention.

FIG. 3 is a diagrammatic showing of the unconscious rotational movementwhich is performed by the hands about the longitudinal axes of theprofiled strips when the wrapper is being opened from the outside.

FIG. 4 is a perspective view showing a broken-off portion of a seamlesstubing, which has two profiled strips and is used in the manufacture ofa wrapper according to the invention.

FIG. 5 shows a finished wrapper, which has been obtained by a fusioncutting and sealing operation from a tubing as shown in FIG. 4.

To enable a sale of the wrapper 1 according to the invention at a mostattractive price, the wrapper is usually made from a seamless tubing 2of plastics material. This tubing is provided with the profiled strips3, 4 while it is being extruded and/or blown. Instead of a tubing ofplastics material, plastics material sheeting may be used as a startingmaterial. The provision of the profiled strips during the manufacture ofthe tubing is recited only as a preferred feature in the claims so thatthey constitute a bar to an unauthorized working of the invention by athird party, who might separately make the fasteners according to theinvention and join them to the wrapper, e.g., by adhering, heat-sealingor stitching. Whereas this would result in a more expensive wrapper, itis known that an unauthorized user will usually accept this disadvantageif it enables him to avoid a protective right. He will be in a positionto bear the higher expenditure because he does not have to spend moneyon research.

The profiled strips 3, 4 are provided on the inside surface 5 of thetubing 2 and extend longitudinally and can be hooked together by anapplication of pressure, as is apparent from FIG. 5.

One profiled strip 3 consists of a unilateral hook '7, which is directedtowards the interior 6 of the bag. The other profiled strip 4 comprisestwo flanges 8, 9, which extend at right angles from the inside surface 5of the wrapper 1 and are disposed on opposite sides of the hook 7 of theopposite profiled strip 3. The flange 8 disposed on the outside of thefastener in the outer part of the wrapper engages the back 26 of thehook 7. The flange 9 which is disposed on the inside of the fastener inthe inner part 6 of the wrapper 1 comprises a unilateral hook tip 11having a concave or re-entrant inside surface.

As is apparent from FIG. 1, the female profiled strip 4 has a smoothback 12. The interengaging surfaces 13, 14 of the two hook-shapedflanges 8, 7 include an acute angle on or [3, respectively, with theassociated inside sur faces of the wrapper 1.

To provide a smooth back for the female profiled strip the die 15 may bedesigned as shown in FIG. 2. An extrusion slot 18, from which the tubing2 emerges, is defined between the die bushing 16 and the die insert 17.In the die insert 17, the slot 19 for the flange 8 and the slot 20 forthe unilateral hook tip 11 having a concave or re-entrant inside surfaceinclude an acuate angle The action of the air stream which prevents acollapsing of the tubing 2 emerging from the extrusion slot 18 holds theflanges 8 and 9 spaced apart by a distance which corresponds to thewidth of the smooth back 12.

If the wrapper according to the invention is not made from a flatsheeting but from an endless tubing 2, which has been integrally formedwith the profiled strips in one operation, the tubing must be severedalong line 21 in FIG. 5 so that two extensions 22, 23 are formed on theoutside of the fastener. To open the wrapper according to the invention,the user instinctively grips the extensions 22, 23 so that the first twojoints of each of its two forefingers are parallel to the two profiledstrips 3, 4, as is apparent from FIG. 3, and the two thumbs have enteredthe gap which has been formed by slitting the tubing. Now each of theextensions 22 and 23 is held between a thumb and forefinger of one hand.To open the fastener, the two extensions 22, 23 are moved apart. In thisoperation, the two hands instinctively perform a rotation about thelongitudinal axes of the fastener strips 3, 4.

The wrapper is closed in the manner which is conventional with pressurefasteners.

The side edges of the individual wrapper shown in FIG. 5 are constitutedby transverse heat-sealed seams 24, 25 formed in a tubing 2 as shown inFIG. 4 on an automatic bag-making machine.

What is claimed is:

1. A reclosable flexible container comprising, a bag body havingflexible walls formed of a plastic film with an upwardly facing opening,releasably interlocking rib and groove elements integrally part of thewalls on facing inner surfaces thereof formed of a resilient materialand separable by applying a force directly to the walls drawing theelements apart and interlockable by pressing the elements together, andexternal flange means on the upper exposed edges of said walls which maybe gripped and drawn apart to separate said elements, said rib elementbeing L-shaped in cross section and defining a first downwardlydepending unilateral hook projecting at right angles from the interiorof the wall with which it is integrally formed toward the opposite wallof the bag body terminating in a flat face which seats against a portionof the opposite interior wall surface, said groove element comprised oftwo flanges projecting at right angles from the interior of the wallwith which they are integrally formed, said flanges being spaced apart adistance corresponding with said portion of the opposite interior wallsurface, one flange being in the form of a fiat bar and seating againstthe back of said first hook, the other flange defining a second upwardlyextending unilateral hook facing and mating with said first unilateralhook along their inside surfaces.

2. A reclosable flexible container according to claim 1 wherein theinside mating surfaces of said hooks form acute angles with the interiorwall surfaces of the bag body.

3. A reclosable flexible container according to claim 1 wherein theinside mating surfaces of said hooks define facing concave surfaces.

(References on following page) Svec et a1.

Svec et a1. Ausuit Freedman.

6 FOREIGN PATENTS 567,093 3/1958 Belgium. 965,258 7/1964 Great Britain.1,132,628 11/1956 France.

DONALD F. NORTON, Primary Examiner.

Examiners.

